The present invention relates to pushbutton switches for use in electrical circuits; for example, an ON-OFF switch in which electrical contact is made when the plunger of the switch is pressed once and contact is broken when the plunger is pressed a second time. It may also be useful for an ON-ON-OFF switch, where there are two different ON positions and an OFF position. It might also be useful for a single pole, double throw switch, where there are two different ON positions and one OFF position. A switch may be an ON-ON switch, where electrical contacts are switched between a common lead and either of two alternate other leads. etc.
A variety of electrical pushbutton switches are well known, with quite a variety of internal operating mechanisms. Small pushbutton switches are desirable for automotive applications, for example, and many of such switches are somewhat noisier than desired. It is preferable to have a pushbutton switch that is quieter than most that are presently available. Many switches have wiping or sliding contact between terminals as the switch is opened or closed. It is desirable to minimize friction in such a wiping contact, if for nothing else but to minimize wear. Light wiping contact pressure is therefore desirable.
It is also desirable that the change of state of the switch does not occur when the plunger of the switch is depressed, but only commences when the plunger is released and moves upwardly. This is known as a xe2x80x9cstable-ON feature,xe2x80x9d which avoids a problem of intermittent contact (e.g., a flickering light bulb) when the plunger of the switch is partly depressed or vibrated.
In an exemplary embodiment, the pushbutton switch comprises a body or housing with two or three electrical terminals, for example. A pushbutton plunger is mounted for reciprocation in the housing for operating the switch. There is a rotatable contact member for contacting the terminals, depending on the rotational position of the contact member for making or breaking an external circuit. A shaft engages the plunger so that it is moved downwardly upon downward depression of the plunger and rotates in response to movement of the plunger. A ratchet rotates the contact member in response to rotation of the shaft.